Water cooled fuel reservoir for a carburetor of a marine propulsion device

ABSTRACT

A water cooled fuel reservoir is provided for a carbureted engine. Water is drawn by a pump from a body of water and caused to flow to a water jacket surrounding a fuel reservoir of the carburetor. The fuel reservoir, or float bowl, stores a quantity of liquid fuel which is cooled by thermal contact with the water in a water jacket of the water reservoir.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally related to a fuel reservoir for acarburetor and, more particularly, to a fuel reservoir for a carburetorwhich is water cooled.

2. Description of the Related Art

Those skilled in the art of marine propulsion devices are familiar withmany different types of cooling systems in which water from a body ofwater is directed in thermal communication with heat emitting componentsof a marine propulsion device. Those skilled in the art of engineshaving carburetors are familiar with the use of fuel reservoirs, orfloat bowls, which store a quantity of fuel for use by the carburetor.These reservoirs typically house a float device which regulates the flowof fuel into the reservoir as a function of the level of fuel in thereservoir. Those skilled in the art of marine propulsion devices arealso familiar with a common problem that can occur as a result ofelevated temperatures under the cowl of an outboard motor. Theseelevated temperatures can result in undesirable fuel vaporization and acondition that is sometimes referred to as “vapor lock”. Vapor lock canoccur in marine propulsion engines, particularly after a prolongedperiod of operation and a shut down followed by a restart of the engine.In addition, operating an engine after a prolonged period of sustainedoperation when the components of the engine are at an elevatedtemperature can result in stalling of the engine. In addition, thoseskilled in the art of marine propulsion devices are also familiar withmany different techniques used to control the temperature of enginecomponents and liquid fuel.

U.S. Pat. No. 3,980,055, which issued to Webb on Sep. 14, 1976,describes a fuel saver and pollution control device. It includes a waterreservoir, a heat exchanger for converting water from the waterreservoir to steam, a conduit for conveying steam to a water trap inwhich steam from the heat exchanger is separated from liquid in thesteam, a conduit for conveying steam from the water trap to thecarburetor, a mixing chamber attached to the carburetor for mixing thesteam with fuel, and a heat exchanger for heating fuel prior to theentry of fuel into the mixing chamber.

U.S. Pat. No. 3,845,745, which issued to Dunlap et al. on Nov. 5, 1974,describes a water injection system for an internal combustion engine. Apump is controlled by manifold pressure to provide water in the outletlines when manifold pressure exceeds a predetermined magnitude andincreasing amounts as the manifold pressure increases further. Waterfeed lines are connected to valving and nozzle means received within aspacer blade mounted to a carburetor such that the water is injecteddirectly into the fuel air mixture and thereby supplied to all of thecylinders or rotary chambers.

U.S. Pat. No. 4,003,357, which issued to Furucz on Jan. 18, 1977,describes a carburetion system for internal combustion motors. Itcomprises a carburetor, a heat exchanger and an admission block. Thecarburetor has a carburetion chamber for each motor cylinder and isprovided with a motor fuel reservoir. A primary circuit individuallyfeeds each chamber from the reservoir while a secondary circuit, whichis independent from the chambers, directly feeds the motor cylinderswith an excess of motor fuel which is fed from the reservoir.

U.S. Pat. No. 4,155,337, which issued to Hensley on May 22, 1979,describes an internal combustion engine having a system forrefrigerating fuel inducted into the carburetor. The spark ignitedinternal combustion engine has a carburetor and a mechanicalrefrigeration system improved with means for cooling the fuel inductedinto the carburetor.

U.S. Pat. No. 4,424,789, which issued to Spalding on Jan. 10, 1984,describes a fuel line preheater. Improvements in fuel heating apparatusfor internal combustion engines utilizes hot water from the enginecooling system as the heat exchanging medium.

U.S. Pat. No. 4,448,153, which issued to Miller on May 15, 1984,describes a water injection system for a combustion engine. It has anintake manifold and carburetor to which water is injected or sprayed byan electrically powered pump receiving water from a reservoir.

U.S. Pat. No. 4,915,063, which issued to Stumpf on Apr. 10, 1990,describes a vapor lock prevention system. It isolates the flow pump fromthe heat radiating engine block in a two cycle, air cooled engine andspaces the fuel pump from the carburetor and injects the fuel directlyagainst the carburetor inlet valve. Application of an additional coolingmeans including air flow and liquid fuel means, may be provided in orderto convey heat away from the fuel pump and therefore maintain the fuelpump temperature below the point at which vaporization pressure exceedsthe impulse pressure generated from the power head. The fuel pump isremoved from the hot carburetor as part of the vapor lock preventionsystem.

U.S. Pat. No. 6,474,317, which issued to Okuzawa et al. on Nov. 5, 2002,describes a heat exchange support plate for engine carburetors. Theengine includes at least one combustion chamber formed by at least afirst member and a second member that moves relative to the firstmember. The second member is coupled to an output shaft such thatmovement of the second member causes the output shaft to rotate. Theengine also includes a cooling system configured to circulate coolantinto thermal communication with at least a portion of the engine. Aninduction system is also included for providing a fuel/air charge to thecombustion chamber. The induction system includes a charge formerconfigured to form the fuel/air charge and a mounting plate that isattached to the carburetor. The mounting plate includes a first coolingpassage that is in communication with the cooling system.

U.S. Pat. No. 6,718,954, which issued to Ryon on Apr. 13, 2004,describes an apparatus for cooling fuel and fuel delivery components. Ituses a cold side of a thermal electric unit prior to entry of fuel intothe fuel delivery components. An excess of cooling is suppliedsufficient to cool the fuel delivery components so as to provide anadditional buffer of cooling for the fuel and to prevent substantialre-absorption of heat after the fuel is cooled.

The patents described above are hereby expressly incorporated byreference in the description of the present invention.

In marine propulsion devices, such as outboard motors, heat can betransmitted from heat emitting components to a fuel storage reservoir,such as the float bowl of a carburetor. This heat can inducevaporization of liquid fuel and, as a result, adversely affect themetering of fuel flowing through the carburetor. If this characteristicis sufficiently affected by undesirable vaporization in the fuelreservoir, or float bowl, it can lead to engine stalling. This conditionis particularly possible when the engine is operating at idle speedfollowing a prolonged period of higher speed operation. Heat generatedduring the high speed operation continues to migrate to other componentsof the outboard motor after the end of the high speed operation andduring the idling period. This heat can raise the temperature of fuel inthe fuel bowl of a carburetor and cause fuel vaporization which, undercertain circumstances, can sufficiently affect the fuel metering to thepoint that the engine is caused to stall.

SUMMARY OF THE INVENTION

A marine propulsion device having an engine and made in accordance witha preferred embodiment of the present invention, comprises a carburetor,a fuel reservoir configured to contain a volume of fuel for use by thecarburetor, a water reservoir disposed in thermal communication with thefuel reservoir, a water pump configured to draw water from a body ofwater in which the marine propulsion device is operating, and an outletconduit connected in fluid communication with the water reservoir. Thewater pump is connected in fluid communication with the water reservoirto direct water from the body of water into the water reservoir.

In a particularly preferred embodiment of the present invention, itfurther comprises a powerhead base configured to support the engine andto direct water to the water reservoir and to the engine. The waterreservoir is configured to direct the water from the water reservoirback to the body of water through the outlet conduit. The waterreservoir can comprise a water jacket substantially surrounding the fuelreservoir. Alternatively, it can comprise a water conduit disposed inthermal communication around the fuel reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully and completely understood froma reading of the description of the preferred embodiment in conjunctionwith the drawings, in which:

FIG. 1 is a highly schematic representation of a marine propulsiondevice showing the various components and the water flow between thosecomponents;

FIG. 2 is a schematic representation of a fuel reservoir;

FIG. 3 shows a water reservoir attached to the fuel reservoir of FIG. 2;

FIG. 4 is an isometric view of a carburetor, a fuel reservoir, and awater reservoir;

FIG. 5 shows the water reservoir and fuel reservoir illustrated in FIG.4;

FIG. 6 is an exploded view of FIG. 5;

FIG. 7 is an exploded view of a more detailed illustration of the waterreservoir and fuel reservoir of a preferred embodiment of the presentinvention;

FIG. 8 is an assembled view of the components illustrated in FIG. 7;

FIG. 9 is a section view of an alternative embodiment of the presentinvention;

FIG. 10 is a graphical representation of a test made with a conventionaloutboard motor fuel system; and

FIG. 11 is a test made with an outboard motor similar to the testillustrated in FIG. 10, but with the present invention used inconjunction with the fuel system.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Throughout the description of the preferred embodiment of the presentinvention, like components will be identified by like referencenumerals.

FIG. 1 is a highly schematic representation of a marine propulsiondevice, such as an outboard motor, and shows the circuit through whichwater travels. A pump 10 is disposed below a level of water 12 in manytypes of outboard motor configurations. The water is caused to flowupward, as represented by arrow 16, through a powerhead base 18 whichcan be an adapter plate. The primary function of the powerhead base 18is to support the cylinder block 20. Another important function of thepowerhead base 18 is to direct water flowing from the pump 10 to thecylinder block 20, as indicated by arrow 24, and to a carburetor 30, asrepresented by arrow 32. The carburetor 30 in FIG. 1 is shownschematically with a water jacket 40 substantially surrounding thecarburetor structure. It should be understood that the carburetor 30 isshown schematically in FIG. 1 and actually represents a carburetor andan associated fuel reservoir, or float bowl. This will be shown ingreater detail below. After passing through the water jacket 40 of thecarburetor float bowl, water is directed back toward the body of water12 as represented by arrow 42.

With continued reference to FIG. 1, water flowing to the cylinder block20 from the powerhead base 18, as represented by arrow 24, is controlledby a thermostat 50. This operation is well known to those skilled in theart and will not be described in detail herein. After water flows inthermal communication with the cylinder block 20, it is directed throughan exhaust system 60 of the marine propulsion device as represented byarrow 62. From there it is returned to the body of water 12.

FIG. 2 is a simplified representation of a fuel reservoir 100 of acarburetor. Although not shown in FIG. 2, it should be understood thatthe reservoir 100 would contain a quantity of liquid fuel for use by thecarburetor and a float which is functionally attached to the carburetorand located within the cavity of the reservoir 100. The float, in amanner well understood by those skilled in the art, controls the flow offuel into the reservoir 100 as a function of the fuel level within thereservoir, or float bowl.

FIG. 3 shows the fuel reservoir 100 associated with a water reservoir110. These two components shown in FIG. 3 are configured to be combinedtogether to define the water jacket 40 as illustrated. An inlet 112 andan outlet 114 are provided to direct water into and through the waterjacket 40. It can be seen that the water within the water jacket 40generally surrounds the fuel within the fuel reservoir 100.

With reference to FIGS. 4-6, a carburetor 130 is shown attached to awater reservoir 110 and a fuel reservoir 100. As described above inconjunction with the simplified illustrations of FIGS. 2 and 3, the fuelreservoir 100 is disposed within the water reservoir 110 to define awater jacket 40 therebetween. It should also be understood that FIGS. 2and 3 are highly simplified schematic representations to show thefunctions of the fuel reservoir 100 and the water reservoir 110 and howa simplified version of this structure can be used to define the waterjacket 40. The illustrations shown in FIGS. 4-6 show a particularlypreferred embodiment of that basic structure. The outer housing of thewater reservoir 110 is shown in FIG. 6 exploded away from the fuelreservoir 100. The inlet 112 and outlet 114 are in slightly differentpositions than the positions illustrated in FIG. 3. Water flows withinthe water reservoir 110 surrounding the outer surfaces of the fuelreservoir 100 when these components are attached together as shown inFIG. 5.

FIGS. 7 and 8 show section views of the preferred embodiment of thepresent invention described above in conjunction with FIGS. 4-6. Theillustrations in FIGS. 7 and 8 are functionally similar to theillustrations in FIGS. 2 and 3, but are directed to a particularpreferred embodiment of the present invention and not to the generalfunctional representation of FIGS. 2 and 3.

The fuel reservoir 100 has a lower section 140. The water reservoir 110is provided with an opening 142 that is shaped to receive the lowerportion 140 of the fuel reservoir 100 and allow access to that lowerportion from a position below the water reservoir 110. The lower portion140 is primarily intended to provide a fuel drain access for the fuelreservoir 100. FIG. 8 illustrates the fuel reservoir 100 disposed withinthe water reservoir 110, defining the water jacket 40, and also showingthe lower portion 140 of the fuel reservoir 100 extending downwardlythrough the opening 142.

FIG. 9 shows an alternative embodiment of the present invention in whichthe water jacket 40 is provided by attaching a conduit 180, which servesas the water reservoir 110, in thermal communication with the fuelreservoir 100. As water is introduced into the inlet 112, it flowsthrough the conduit 180 around the fuel reservoir 100, in a spiral path,and leaves the water jacket 40 through outlet 114.

FIGS. 10 and 11 are graphical representations of actual empiricaltesting of a system that is generally similar to the system shown inFIGS. 2 and 3. Engine speed is represented by line 200 in FIG. 10. Ascan be seen, at approximately 200 seconds from the beginning of thetest, the engine speed is increased from an idle speed, below 1500 RPM,to an operating speed of approximately 5500 RPM. Dashed line 202represents the ambient temperature surrounding the marine propulsiondevice during the test. Dashed line 204 represents the air intaketemperature under the cowl of the outboard motor. Dashed line 206represents the temperature of the surface of the air intake manifold ofthe engine, and dashed line 208 represents the temperature of the fuelflowing into the fuel reservoir. Dashed line 210 represents thetemperature of the fuel within the float bowl, or fuel reservoir, of thecarburetor.

With continued reference to FIG. 10, it can be seen that with theincrease in RPM at approximately 200 seconds, dashed lines 206 and 208temporarily decrease in temperature and then increase during the periodof time when the engine is operating at approximately 5500 RPM.Similarly, dashed line 210, which represents the temperature of the fuelwithin the float bowl or fuel reservoir increases during the time ofhigh RPM running. This continues throughout the duration of increasedengine speed, from approximately 200 seconds to approximately 1300seconds. After the engine is slowed to idle speed again at approximately1300 seconds, the fuel temperature within the fuel reservoir,represented by dashed line 210, continues to increase. This is a resultof heat being transferred from heat emitting components to thecarburetor and its float bowl. This increases the temperature of thefuel within the float bowl and, under certain conditions, induces itsvaporization. This, in turn, can adversely affect the fuel meteringcapability of the carburetor. Under certain adverse conditions, this canlead to the stalling of the engine. The primary intent of the presentinvention is to reduce the temperature of the fuel within the floatbowl, represented by dashed line 210, during and after periods ofincreased engine speed, such as the period between 200 seconds and 1300seconds in FIG. 10.

FIG. 11 is a graphical representation of a test made with an engineincorporating the present invention. As can be seen, line 200 in FIG. 11is generally similar to line 200 in FIG. 10, indicating that the enginespeed profile during the test between times 200 seconds and 1300 secondsis generally identical to that used for the test illustrated graphicallyin FIG. 10. Similarly, the undercowl intake air temperature 204 issimilar to that shown in FIG. 10. Although the absolute magnitudes oftemperature represented by dashed lines 206 and 208 are slightlydifferent than those represented by dashed lines 206 and 208 in FIG. 10,their overall change in behavior are generally similar to thoserepresented in the test illustrated in FIG. 10. Similarly, the roomtemperature 202 is similar to that illustrated in FIG. 10 and describedabove. However, the fuel temperature 210 within the carburetor fuelreservoir behaves significantly differently when the present inventionis used in FIG. 11 as compared to when the present invention is not usedin FIG. 10. The flow of water through the water jacket 40, describedabove in conjunction with FIGS. 2, 3, 7 and 8 prevent the fueltemperature from rising by the same magnitude it does in FIG. 10 betweentimes 200 seconds and 1300 seconds. Therefore, during high engine speed,the flow of water maintains the fuel temperature in the float bowl at asignificantly lower temperature and when the present invention is notused. In addition, immediately after the engine speed is reduced back toidle, at approximately 1300 seconds, the temperature of the fuel withinthe fuel reservoir actually decreases as compared to the continuedincrease illustrated by dashed line 210 in FIG. 10 after the enginespeed is reduced to idle speed.

With continued reference to FIGS. 10 and 11, it should be understoodthat the water pump 10, described above in conjunction with FIG. 1, istypically driven by the crankshaft of the engine. Therefore, when theengine speed increases, the pump speed also increases. In addition,after the engine speed is again reduced to idle speed, the pumpcontinues to induce the flow of water through the water jacket 40, butat a lower speed which is typically controlled by the crankshaft speed.As long as the engine is operating, at any speed, the water pump 10 isoperating. Therefore, even at idle speed, water is being circulatedthrough the water jacket 40 to remove heat from the fuel reservoir 100and the liquid fuel contained therein. Therefore, the fuel is maintainedat an efficient operating temperature and fuel vaporization issignificantly inhibited. When the engine is off, the water within thewater reservoir 110 continues to absorb heat from the fuel reservoir100.

The marine propulsion device incorporating the present inventioncomprises a carburetor. Those skilled in the art of engines and, moreparticularly, marine propulsion engines, are familiar with thesignificant differences between carbureted engines and engines whichutilize fuel injectors. Fuel injection systems often use a reservoirreferred to as a fuel vapor separator. Fuel vapor separators serve asignificantly different function than float bowls or fuel reservoirs forcarburetors. Typically, fuel vapor separators incorporate fuel pumps toraise the pressure of the fuel from the reservoir to the injector.Carburetors do not incorporate pumps of this kind. In addition, fuelvapor separators are vented to allow the separation of fuel vapor fromliquid fuel. Fuel reservoirs, or float bowls, of carbureted systems arenot intended to perform this function. Those skilled in the art of fuelinjection systems are aware that water cooling can be used to reduce thetemperature of a fuel vapor separator. However, carbureted engines havenot been cooled with water jackets associated with their float bowls, orfuel reservoirs.

With reference to FIGS. 1-11, it can be seen that a marine propulsiondevice made in accordance with a preferred embodiment of the presentinvention comprises a carburetor 130, a fuel reservoir 100 configured tocontain a volume of fuel for use by the carburetor 130, a waterreservoir 110 disposed in thermal communication with the fuel reservoir100, and a water pump 10 configured to draw water from a body of water12 in which the marine propulsion device is operating. The water pump 10is connected in fluid communication with the water reservoir 110 todirect water from the body of water 12 into the water reservoir 110. Inaddition, the present invention comprises an outlet conduit 114 which isconnected in fluid communication with the water reservoir. A powerheadbase 32 is configured to support the engine 20 and to direct water tothe water reservoir 110 and to the engine 20. The water reservoir 110 isconfigured to direct the water from the water reservoir, or water jacket40, back to the body of water 12. The water reservoir 110 can comprise awater jacket 40 substantially surrounding the fuel reservoir 100.Alternatively, the water reservoir 110 can comprise a water conduit 180disposed around the fuel reservoir 100.

Although the present invention has been described in particular detailand illustrated to show various alternative embodiments of the presentinvention, it should be understood that alternative embodiments are alsowithin its scope.

1. A marine propulsion device having an engine, comprising: acarburetor; a fuel reservoir configured to contain a volume of fuel foruse by said carburetor; a water reservoir disposed in thermalcommunication with said fuel, said water reservoir comprising a waterjacket substantially surrounding said fuel reservoir; a water pumpconfigured to draw water from a body of water in which said marinepropulsion device is operating, said water pump being connected in fluidcommunication with said water reservoir to direct said water from saidbody of water into said water reservoir; and an outlet conduit connectedin fluid communication with said water reservoir.
 2. The marinepropulsion device of claim 1, further comprising: a powerhead baseconfigured to support said engine and to direct said water to said waterreservoir and to said engine.
 3. The marine propulsion device of claim1, wherein: said water reservoir is configured to direct said water fromsaid water reservoir back to said body of water.
 4. (canceled)
 5. Themarine propulsion device of claim 1, wherein: said water reservoircomprises a water conduit disposed around said fuel reservoir.
 6. Amarine propulsion device having an engine, comprising: a carburetor; afuel reservoir configured to contain a volume of fuel for use by saidcarburetor; a water reservoir disposed in thermal communication withsaid fuel reservoir, said water reservoir comprising a water jacketsubstantially surrounding said fuel reservoir; a water pump configuredto draw water from a body of water in which said marine propulsiondevice is operating, said water pump being connected in fluidcommunication with said water reservoir to direct said water from saidbody of water into said water reservoir; a powerhead base configured tosupport said engine; and an outlet conduit connected in fluidcommunication with said water reservoir.
 7. The marine propulsion deviceof claim 6, wherein: said powerhead base is configured to direct saidwater to said water reservoir and to said engine.
 8. The marinepropulsion device of claim 7, wherein: said powerhead base is an adapterplate.
 9. The marine propulsion device of claim 6, wherein: said waterreservoir is configured to direct said water from said water reservoirback to said body of water.
 10. (canceled)
 11. The marine propulsiondevice of claim 6, wherein: said water reservoir comprises a waterconduit disposed around said fuel reservoir.
 12. A marine propulsiondevice having an engine, comprising: a carburetor; a fuel reservoirconfigured to contain a volume of fuel for use by said carburetor; awater reservoir disposed in thermal communication with said fuelreservoir, said water reservoir comprising a water jacket substantiallysurrounding said fuel reservoir; a water pump configured to draw waterfrom a body of water in which said marine propulsion device isoperating, said water pump being connected in fluid communication withsaid water reservoir to direct said water from said body of water intosaid water reservoir; an outlet conduit connected in fluid communicationwith said water reservoir; and a powerhead base configured to supportsaid engine and to direct said water to said water reservoir and to saidengine.
 13. The marine propulsion device of claim 12, wherein: saidmarine propulsion device is an outboard motor.
 14. The marine propulsiondevice of claim 13, wherein: said water reservoir is configured todirect said water from said water reservoir back to said body of water.15. (canceled)
 16. The marine propulsion device of claim 14, wherein:said water reservoir comprises a water conduit disposed around said fuelreservoir.